The present invention relates to a conductive film, a display device equipped with the conductive film, and a method for determining a pattern of a conductive film. Specifically, the present invention relates to a conductive film, which is used as a mesh transparent conductive film, and has a mesh pattern designed in consideration of an electrode such that a spectral intensity and a frequency of visually recognized moire are respectively within predetermined ranges of intensity and frequency, a display device equipped with the conductive film, and a method for determining a pattern of a conductive film.
Examples of a conductive film installed on a display unit of a display device (hereinafter, also referred to as a display) include a conductive film for electromagnetic wave-shielding and a conductive film for a touch sensor (touch panel) (for example, see Patent Literatures 1 to 3).
JP 2009-117683 A (Patent Literature 1) filed by the applicant of the present application discloses a conductive film for electromagnetic wave-shielding having an electromagnetic wave-shielding pattern formed of a mesh-like conductive metal thin film, and discloses that a second pattern, which is generated from second pattern data in which the relative distance between spectral peaks of two-dimensional Fourier spectra (2DFFT Sp) of the respective pattern data of a first pattern such as a pixel array pattern (for example, a black matrix (hereinafter, also referred to as BM) pattern) of a display and the second pattern such as the electromagnetic wave-shielding pattern is greater than a predetermined spatial frequency, for example, 8 cm−1, is automatically selected.
JP 2009-117683 A also discloses that when the relative distance is not greater than the predetermined spatial frequency, changing of one or more of a rotation angle, a pitch, and a pattern width of the second pattern data to generate new second pattern data is repeated until the relative distance is greater than the predetermined spatial frequency.
In this way, in JP 2009-117683 A, it is possible to automatically select an electromagnetic wave-shielding pattern that can suppress the occurrence of moire and that can avoid an increase in surface resistivity or degradation in transparency.
Meanwhile, in a conductive film for a touch panel, in view of quick responsiveness, high resolution, increase in size, low production cost, and the like, instead of the conventional transparent ITO (indium tin oxide), opaque conductive materials such as metals are used as mesh-like wiring materials. In order to realize a touch panel by using such a conductive film, the conductive film needs to have resolution for detecting a touched position. For making the conductive film function as a transparent conductive film such as ITO by using mesh-like conductive wiring of the conductive film, with respect to the whole surface of solid mesh-like wiring, cut portions need to be provided in specific mesh-like wiring so as to form disconnections, and in this way, a wiring region for detection corresponding to the aforementioned resolution needs to be separated from a dummy wiring region that does not contribute to the detection.
In the touch panel disclosed in JP 2010-097536 A (Patent Literature 2), within each of a plurality of dummy wiring regions surrounded by 2 types of wiring for detection made of a metal (an opaque conductive material) that are provided to cross each other via an insulating layer on both sides thereof, isolated wiring is arranged in a state of being parallel or perpendicular to the wiring for detection or in a state of inclining by 45° with respect to the wiring for detection. In this way, cut portions (breaks) are formed between a wiring region for detection composed of 2 types of wiring for detection and a dummy wiring region, and consequently, the wiring region for detection and the dummy wiring region are separated from each other.
According to JP 2010-097536 A, in this way, it is possible to obtain a touch panel which has a high response speed, can reduce display unevenness or moire, has high visibility, and is easily made into a large-sized touch panel.
JP 2010-262529 A (Patent Literature 3) discloses a conductive film (planar body) for a capacitive type touch panel (a touch switch). The conductive film is divided into a plurality of regions of a conductive portion, in which network (mesh)-like electrodes composed of conductive wires are disposed at a predetermined interval in a state of being approximately parallel to each other, and regions of a non-conductive portion each of which is disposed between the regions of a conductive portion. The regions of a non-conductive portion include a plurality of cut portions (breaks) that cut the conductive wires in the form of islands, and by the cut portions, the regions of a non-conductive portion (dummy wiring regions) can be insulated from the regions of a conductive portion (wiring regions for detection) adjacent thereto.
According to JP 2010-262529 A, in this way, it is possible to improve visibility by preventing the visibility from deteriorating due to the occurrence of variation of mesh density (deviation of mesh), and to provide a planar body and a touch switch that can be efficiently manufactured.